Obligatory Checks For Initial Start-Up - Mitsubishi Electric NX-W Installation And Operating Manual

UM_NX-W_00_05_19_ML
7.3 Control circuit interlocking
In order for the guarantee to be valid:
•
connect the calibrated flow switch to the specific terminals of the control circuit (if not included in the standard supply)
•
connect the auxiliary pump contacts to the specific terminals of the control circuit (if present in the wiring diagram).
•
unit input connectors (remote ON/OFF, flow switch, pumps enable, etc..) must be clean and single contacts for each unit (never make a parallel
connection to more than one machine with a single enable)
It is advisable for the connection cables of the above safety devices to be laid separately from any power cables. Otherwise, screened cables should be used. To make serial
connections, use only screened cables with characteristic impedance of 120 ohm. The maximum length of the cable that connects safety devices to the farthest away unit must
not exceed 1000 metres.
These devices must be connected to the first unit by a single serial cable, which then goes on to connect subsequent units. The screens of each stretch must be connected to
each other but not to the unit terminal block. One of the ends of these screens must be grounded.
If the remote ON/OFF control is used, lay cables following the same method as the flow switch cables.
Moreover, for remote ON/OFF control from an external contact or from the serial protocol control, the following minimum delays must be complied with:
•
Delays between 2 subsequent start-ups: 15 minutes
•
Delay between shut-down and start-up: 3 minutes
Furthermore, the pump must be operated for at least 1 minute before starting the unit and be switched off 1 minute after the unit is shut down, otherwise the guarantee
will be considered null and void.
7.4 Input voltage phase difference
Do not operate the electric motors when the voltage phase difference is greater than 2%. Use the following formula to check:
Example: Rated mains voltage 400 - 3 - 50
AB = 409 V; BC = 398 V; AC 396 V
average voltage = (409 + 398 + 396) / 3 = 401 V
IMPORTANT:
If the mains voltage has a phase difference greater than 2%, contact the electricity company. If the unit is operated with a voltage phase difference of more than 2%
THE GUARANTEE SHALL BE CONSIDERED NULL AND VOID.
Before starting up the unit, it is advisable to check that electrical systems have been implemented to guarantee conformity with the Electromagnetic Compatibility Directive
(2004/108/EC).
7.5 Phase sequence checks for units with scroll compressors
After starting, check that the noise level of the compressor is normal and that the inlet temperature is lower than the outlet temperature. If not, invert a phase.
NOTE: some compressors are fitted with a phase sequence control device that displays "overload alarm" if the phases are inverted.
8

OBLIGATORY CHECKS FOR INITIAL START-UP

MEHITS tests the cooling circuit for leaks after final assembly of the unit at the production site. An additional test must be carried out before start-up to check for leaks caused by
faults created during transport or installation.
MITSUBISHI ELECTRIC HYDRONICS & IT COOLING SYSTEM S.p.A.
Max voltage difference from the average
% difference = ------------------------------------------------ x 100
average voltage
(409 - 401)
difference % = ------------------- X 100 = 1.99
401
A B C
43
EN
Translation of the original instructions